Pumps: How to Select the Right Pump

This tutorial will take you step-by-step through the process of selecting the right pump for your irrigation system.  (Not looking for an irrigation pump?  Most of the pump principles presented here apply to any pump use, not just irrigation.)  Most irrigation pump situations you may encounter we will cover, but you will need to do a bit of reading.  That is the do-it-yourself way.  If you don’t want to take the time to educate yourself you should stop here, and hire a local pump professional to come out to your property, do the research necessary, and recommend a pump for you.  There is no shame in having a pro help you if the job is over your head or just too time consuming!

NOTE: There is no “easy way” to select a pump.   There are two things you must absolutely know in order to select the right pump: the irrigation system operating pressure and the system flow rate.   If anyone tries to tell you what pump you need without establishing what your needed flow (GPM or l/m) and pressure (PSI or bars) are they are just guessing.  That’s like determining how many marbles it takes to fill a jar.  Without knowing how big the jar is, and how big the marbles are, all you can do is take a wild guess!

Now first let’s start by getting you around the huge beginner’s mistakes.

Warning- don’t make these major mistakes!

There are 3 major errors people often make in regards to irrigation pumps. All of these are VERY expensive errors to fix. So let’s get you on the right track from the very beginning!

Plan First!

Do not buy a pump until you have determined your exact water needs for flow and pressure!  Many people every year lose lots of money because they bought a pump before they designed their irrigation system, then discovered it wasn’t the right type or size.   A pump must be sized for the exact pressure and flow requirements of your irrigation system.  Way too many people ask “what horsepower do I need?”  Newbie question!  Pumps aren’t selected by horsepower.  You need a pump that produces the correct amounts and ratios of water flow and water pressure.  It might seem obvious, but our experience indicates it isn’t.   So figure out your water requirements first, then purchase the pump second!

Pump Labels:

Many (most?) prepackaged off-the-shelf pumps have misleading performance labels. They aren’t exactly lying to you, they just aren’t being very clear.  Often a pump or the pump’s package will be labeled with something similar to “20 GPM, 55 PSI”.*  Or it may say “20 GPM, 127 feet of lift”. In most cases the word “or” should be added. What they mean is 20 GPM or 55 PSI. This is critical! There is a huge difference in performance between a pump that produces 20 GPM at 55 PSI, and a pump that produces 20 GPM or 55 PSI.  You may even see this misleading information stamped right onto the pump identification tag on the pump body!

Think about it in terms of a car. What if you are looking to buy a car and see one with the performance listed as “seats 5, goes 80 mph”?  So you buy the car, load it up with 4 buddies and quickly discover it won’t go over 20 MPH.  What gives?  Well what they meant was it carries 5 passengers OR goes 80 MPH.  They didn’t lie to you, they just didn’t really tell you the whole truth either.  The car goes 80 MPH with 1 passenger but with 5 passengers it won’t go more than 20 MPH.   See the difference?

*We’ll explain GPM & PSI later.  All this will make much more sense after you have read this article, but for now you need to be aware of this mislabeling problem right up front.  Watch out for the wording on the pump labels!

So called “Irrigation Pumps”:

A number of websites and stores sell pumps that they call “irrigation pumps” or “sprinkler pumps.” These are typically small, inexpensive pumps designed to operate a single, small sprinkler head on the end of a garden hose.  They are not made for sprinkler systems with more than one sprinkler.

Typically pumps that are suitable for sprinkler systems are marketed as “high pressure pumps”.  Knowing that will save you some time when you start shopping.

OK, warnings complete, let’s get started!

Selecting a Pump – Overview

  1. Learn enough about pump hydraulics to understand the rest of the tutorial.
  2. Determine the pressure and flow your irrigation system requires.
  3. Select the type of pump (end-suction, submersible, turbine, etc.)
  4. Select a pump model and size.
  5. Select the method of controlling the pump.  (Ie; turning it on and off.)
  6. Go shopping.

Each step builds on the one before it.  We’ll guide you through it all, just keep reading…

Go to the next page –>   Basic Pump System Hydraulics